Cleaning efficiency of cellulose pre-treatment of modern trees

Dr Helene Svarva1, Professor Pieter Meiert Grootes1, Dr. Martin Seiler1, Dr. Marie-Josée Nadeau1

1National Laboratory For Age Determination – Ntnu, Trondheim, Norway

The AMS radiocarbon measurement of single ring and sub-annual tree-ring samples demands that the cellulose preparation method be time-efficient, effective in removing contamination, and have high enough yields for wood in different states of preservation. The pre-treatment of wood into hemicellulose allows fast processing with generally good results. However, when a very high accuracy is needed, for instance when measuring sub-annual samples over the bomb spike, the more elaborate extraction of alpha-cellulose, which is the most stable of the polymers that comprises wood cellulose, might be required. We explored the addition of a 17.5% sodium hydroxide step to the base-acid-base-acid-bleach (BABAB; Němec et al. 2010) cellulose preparation. This should dissolve and allow the extraction of the low-weight polymer fractions in the hemicellulose. This extra step was tested on whole ring samples and on samples of early-wood and late-wood in a Scots pine tree (Pinus sylvestris L.). It increases efficiency in removing bomb-contaminated fractions from modern pre-bomb tree rings compared to the standard BABAB extraction of hemicelluloses. It is therefore suitable for the pretreatment of modern samples where a high accuracy is required with moderate effort. For subfossil wood, the extraction yields using this preparation method depend heavily on the state of cellulose preservation in the sample. We here compare the results and yields of different variations of this method, including the use of solvents.

References
Němec, M., Wacker, L., Hajdas, I., & Gäggeler, H. (2010). Alternative Methods for Cellulose Preparation for AMS Measurement. Radiocarbon, 52(3), 1358-1370. doi:10.1017/S0033822200046440


Biography:

Researcher working at the National Laboratory for Age Determination in Trondheim. My interests are tree rings, dendroclimatology and radiocarbon.

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Date

Nov 08 - 19 2021